Hundreds of anti-abortionists, who claim there is no demand for Marie Stopes in Northern Ireland, have organised a mass rally to show their opposition.

Paula Davison, from the Precious Life lobby group, said demonstrators who will be carrying placards have been urged to behave with dignity.

Northern Ireland's first private abortion clinic will officially open on Thursday

She said: "It is a prayer rally so obviously it is going to be very peaceful. We do not want any violence or intimidation - definitely not in our name.

"It is hard to say how many people will be there but we are expecting quite a number. It will be from 10am until 4pm."

Precious Life said the protest, which has been promoted through social networking sites, is likely to be a one-off event.

Ms Davison added: "I think it will be the only one in the foreseeable future."

In Northern Ireland abortion is strictly controlled. The procedure is only permitted if the life or mental health of the mother is at serious risk.

Marie Stopes said its new facility, which is headed by former Progressive Unionist Party MLA Dawn Purvis, will operate within the current legal framework, providing medical not surgical terminations up to nine weeks' gestation with aftercare including counselling.

Stormont Health Minister Edwin Poots has said the new centre will be closely regulated and warned that any breaches of the law could be punishable with a maximum sentence of life imprisonment.

Liam Gibson, development officer with the Society for the Protection of Unborn Children (SPUC), said his organisation was determined to have the new clinic closed.

He said: "We are against the opening of the Marie Stopes clinic and we are committed to seeing it shut down as an abortion clinic. Abortion cannot be offered as a routine service under the law. It is incompatible with the law."

As yet, legal challenges have not been launched by Precious Life or SPUC to prevent Marie Stopes from operating in Belfast.

Mr Gibson added: "We are in close contact with members of the Assembly and there is a political will that Marie Stopes are not going to open as an abortion clinic in Belfast.

"We will keep the pressure on. Through litigation and legislation we will eventually make sure that abortions are not carried out by Marie Stopes or any other private business in Northern Ireland."

Meanwhile, pro-choice campaigners have said they will not be holding a counter-demonstration out of respect for the women wanting to use the centre.

Goretti Horgan, a spokeswoman for the Alliance for Choice, said they will have a show of support for Marie Stopes during a trade union anti-austerity march in Belfast on Saturday.

She said: "We want to see the 1967 Abortion Act extended to Northern Ireland and Marie Stopes coming here is very important and symbolic.

"Abortion is not a black and white issue. I think that people understand that women's lives are different now and that sometimes women have very little choice but to have abortions."